Cyclic diol diester lubricants



United States Patent C) CY CLIC DIOL DIESTER LUBRICANTS Kent C. Brannock, Klngsport, Tenn assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application November 29, 1957 Serial No. 699,530

6 Claims. 01. 260-410 siderable amount of volatile material which is lost at high temperatures. Hydrocarbon lubricating oils particularly sufier where extreme conditions of temperature are encountered, such as in turbo-jet aircraft engines. High engine temperatures in turbo-jet aircraft engines are desirably employed to increase engine efliciency. In such a high temperature use, conventional hydrocarbon lubricating oils suffer thermal and oxidative breakdown to an undesirable degree.

In recent years a number of synthetic ester lubricants have been proposed to overcome some of the objections to hydrocarbon lubricating oils.

. It is an object of this invention to provide a new group of synthetic ester materials that have particular utility as lubricants and which are not subject to many of the disadvantages inherent to hydrocarbon lubricating oils. It is another object of the invention to provide novel synthetic ester lubricants which have lower pour points than hydrocarbon lubricants of comparable viscosity.

It is another object of this invention to provide a new class of synthetic ester lubricants having improved resistance to thermal degradation.

It is likewise an object of this invention to provide new synthetic ester lubricants especially adapted to meet the high temperature requirements desired for lubricating turbo-jet engines and for related uses.

Other objects will be apparent from the description and claims which follow.

CH CH O B C C O 0 CH, CHIOER O l l emails {I Hr and O CHrOEB 0 Hr J; CHrO ii R Wherein R is an alkyl group containing 6 to 11 carbon atoms. 1,1-cyclopentanedimethanol di-n-heptanoate; l,l-cyclopentanedimethanol di-n-octanoate; l,l-cyclopentanedimethanol dipelargonate; 1,1-cyclopentanedimethanol din-decanoate; 1,1-cyclopentanedimethanol di-n-undecanoate; 1,1-cyclopentanedimethanol di-n-dodecanoate; 1,1- cyclohexanehexanedimethanol di-n-heptanoate; 1,1-cyclohexanedimethanol di-n-octanoate; l,l-cyclohexanedimethanol dipelargonate; 1,1-cyclohexanedimethanol di-n-decanoate; 1,1-cyclohexanedimethanol di-n-undecanoate; 1,1- cyclohexanedimethanol di-n-dodecanoate; 2,2-norcamphenedimethanol di-n-heptanoate; 2,2-norcamphanedimethanol -di-n-octanoate; 2,2-norcamphenedimethanol dipelargonate; 2,2-norcamphanedimethanol di-n-decanoate; 2,2-norcamphanedimethanol di-n-undecanoate' and 2,2- norcamphanedime'thanol di-n-dodecanoate.

The present synthetic diesters of cyclic diols have considerable utility as lubricants. By varying the choice of the acyl moiety with which the 1,1-cyclopentanedimethanol; 1,1-cyclohexanedimethanol and 2,2-norcamphanedimethanol are esterified, lubricants having a wide range of viscosities and pour points can be obtained. The present diesters can be used directly as lubricants or they can be blended with other lubricants. If desired, minor proportionate amounts of such conventional lubricant additives as antioxidants, extreme pressure additives, viscosity index improvers, thickeners, anticorrosion agents and related materials can be incorporated into the present diester lubricants.

The viscosity and pour point characteristics of typical synthetic diesters of cyclic diols embodying this invention are illustrated in Table 1 below. In addition, a comparison is made with a typical hydrocarbon oil of comparable viscosity.

As can be seen from the'data set out in Table l,' the present synthetic lubricants have excellent viscosity and pour point characteristics.

The improved thermal stability of the present synthetic diester lubricants is illustrated by the data in Table 2 and Table 3 below. For purposes of comparison,

two known diester lubricants, namely, bis-(2-ethylhexyl)- sebacate and 2,2,4-trimethyl-1,3-pentanediol dipelargonate, as well as an 8 carbon branched chain oxo alcohol, diester of cyclohexane-l,1-diacetic acid, are compared. with typical diesters of the present invention by the data.

in Table 2 and Table 3.

Patented Nov. 10, 1959 Typical cyclic diesters of the invention include:

3 TABLE 2 Percent change in 100 F. viscosity Ester after 8 hour heating at indicated temperatune Bis-(Z-ethylhexyl) sebaeate 18% at 600 F. 3,2.4-Trlmethyl-L3-pentanedlol dipelargonate 16% at 550 F. Carbon oxo alcohol diester of 1,1-cyclohexanediacetic acid -19% at 600 F. 1,1-Cyclogentanedimethanol dlpelargonate l.4 0 at 600 F. 1,1-Cyclo exanedimethanol dl-n-octanoate +06% at 600 F. 2,2'Norcamphanedlmethan0l di-n-octanoate +29% at 600 F.

TABLE 3 Percent Decomposition/hour at- Ester 500 F. 525 F. 550 F. 575 F. 600 F.

lBis-(Z-ethylhexyl) sebacata. 0. 03 0. 11 0. 13 0. 59 1. 3 2,2,4-Trtu1ethyl-L3-pentanediol dlpelargonate 0.1 1. 09 8 Carbon 0x0 alcohol diester oi 1,1-cyolohezanediacetlc m-ld 0. 04 0- 17 1. 6 1,1-Cyclopentanedlmethano] dlpelargonate 0.02 0. 03 0. 04 1,1-Cyclohexanedlmethanol dl-n-octanoate 0. 003 0. 01 2,2-Norcamphanedlmethanol di-n'm'tannatp 0. 01 0.

The data in Table 2 and Table 3 point-up the fact that k the synthetic lubricants of the present invention can be utilized at high temperatures as they possess excellent resistance to thermal degradation The pour point data set out in Table 1 was determined by ASTM Method D-97-47 and the viscosity data set out in Table 1 and Table 2 was determined by ASTM Method D-88-44. The data set out in Table 3 concerning the percent decomposition/hour of the various esters was based on the determination of the acid produced on heating samples of the various esters under nitrogen for eight hour periods.

The following examples illustrate the preparation of typical diesters of the present invention from starting materials known in the art.

Example I A mixture of 147 g. of cyclopentanecarboxaldehyde, 331 g. of 36% formalin and sufficient methanol to make a homogeneous solution, was added dropwise to a stirred solution-oi 105 g. of potassium hydroxide in 375 ml. of methanol over a 40 minute period. The resulting mixture was then heated under reflux for 5% hours, cooled, and 400 m1. of water added. The mixture was thereafter distilled until removal of the methanol was complete, and on cooling the residue, 1,1-cyclopentanedimethanol crystallized out. The 1,1-cyclopentanedimethanol crystals were removed from the reaction mixture by filtration, washed in cold water, and recrystallized from a hexane-chloroform mixture to give 123 g. of 1,1- cyclopentanedimethanol having a melting point of 98.5- 99.5 C. Thereafter, 1,1-cyclopentanedimethanol so prepared was esterified to prepare the present diester lubricents.

(a) A mixture of 156 g. (1.2 moles) of 1,1-cyclopentanedimethanol, 346 g. (2.4 moles) of n-octanoic acid and ml. of xylene was refluxed in a reactor fitted with a Dean-Stark separator until water ceased to be evolved from the reaction mixture. The theoretical amount of water, 43 ml., was collected after 3 hours and the temperature of the reaction mixture had risen to 272 C. The resulting mixture was cooled, and thereafter washed with ml. of a 5% sodium hydroxide aqueous solution and then with 100 ml. of water. The xylene was stripped ofr by distillation and the resulting distillation residue further distilled in a molecular still to give 1,1- cyclopentanethanol dincctanoate boiling at 97- atoms.

gyclopentanedimethanol were reacted to prepare 1,1-cyclopentanedimethanol dipelargonate boiling at 107-110" C. at 6 microns of mercury and having a 1.4575.

Example 2 A mixture of 1.2 moles of 1,1-cyclohexanethanol and 2.4 moles of n-octanoic acid was reacted and workedup as described in Example 1 (a) above. The 1,1-cyclohexanedimethanol di-n-octanoate prepared boiled at C. at 5.4 microns of mercury and had n 1.4601.

Example 3 A 137 g. sample of -bicyclo(2,2,1)-5-heptene-2,2-dimethanol was hydrogenated over 15 g. of Raney nickel at 100 C. under a pressureot 1,000 p.s.i. to give 2,2- norcamphanedimethanol. A mixture of 1.2 moles of 2,2- norcamphanedimethanol and 2.4 moles of n-octanoic acid was reacted and worked-up as described in Example l (a) above. The 2,2-norcamphanedimethanol dicctanoate prepared boiled at -136 C. at 1 micron off mercury and had 92 1.4670.

While the above examples describe the esterification of 1,1 cyclopentanedimethanol; 1,1 cyclohexanedimethanol and 2,2-norcamphanedimethanol with particular organic acids, it is to be understood that in a like mer these cyclic diols can be esteiified with any organic acid having the formula RJJOOH wherein R is an alkyl group containing 6 to ll carmn Likewise, mixtures of such acids can be u to prepare the present diester lubricants.

Thus, by means of this invention, a novel and hiy useful group of synthetic diester lubricants is provided. The improved physical characteristics make the present diesters eminently suitable for use as lubricants in appli= cations where hydrocarbon lubricating oils are now used, as well as in high temperature applications where hydrocarbon lubricating oils are completely unsuitable. Be cause of their improved thermal stability at high temperatures, the present diester lubricants have particular utility for use in turbo-jet aircraft engines and for related high temperature applications.

The invention has been described in considerable d with particular reference to certain preferred embodiments thereof, but it will be understood that variations and modifications can be efiected within the spirit and scope of the invention as described hereinabove and as defined in the appended claims.

I claim:

1. A synthetic lubricant composition of high th stability consisting essentially of a diester selected from the group consisting of compounds of the formulas:

O OHs C sO R C O L l omoiia and wherein R is an alkyl group zit-t": 6 to ill corhon atoms.

2. A synthetic lubricant composition of high thermal stability consisting essentially of a diester of the formula:

4. A synthetic lubricant composition of high thermal stability consisting essentially of 1,1-cyclopentanedimeth- O anol di-n-octanoate. II

wherein R is an alkyl group containing 6 to 11 carbon 10 atoms.

3. A synthetic lubricant composition of high thermal stability consisting essentially of a diester of the formula:

wherein R is an alkyl group containing 6 to 11 carbon atom!- 5. A synthetic lubricant composition of high thermal 5 stability consisting essentially of 1,1-cyclopentanedimethanol dipelargonate.

6. A synthetic lubricant composition of high thermal stability consisting essentially of 2,2-norcamphanedimethanol di-n-octanoate.

Refercnces Cited in the file of this patent UNITED STATES PATENTS Staib et al Mar. 13, 1956 Roelen et al Dec. 24, 1957 FOREIGN PATENTS Great Britain May 23, 1945 France Feb. 22, 1955 

1. A SYNTHETIC LUBRICANT COMPOSITION OF HIGH THERMAL STABILITY CONSISTING ESSENTIALLY OF A DIESTER SELECTED FROM THE GROUP CONSISTING OF COMPOUNDS OF THE FORMULAS: 